‘Stunning’ earth block technology employed

By: Paul Weideman
Published online: Sunday, August 05, 2012
Appeared in: Home, Santa Fe Real Estate Guide
Edition: August 2012 Vol. 15 No. 5

This alternative building method seems just too simple. A worker digs soil using a Bobcat loader and dumps it into a trailer-mounted Earth Press machine. Each minute, four or five blocks of compressed earth pop out. A roller conveyer takes them right to the spot where workers are stacking them to build a wall.

In June, architect and contractor Ed Boniface, Boniface + Associates, marveled at the process as a ranch house he designed went up near Puerto de Luna, about 15 miles south of Santa Rosa.

Neither rebar nor mortar was necessary. “When the earth is compressed with the hydraulic press in the machine, the moisture on the surface facilitates adherance,” he said. “This thing puts out 2,400 blocks in a day. These guys are laying up walls as fast as they can. It’s absolutely stunning.

“I was terrified at first at this idea of just stacking stuff up, but I contacted the State Construction Industries Division and the more research I did, the better it all looked.”

The walls are now complete and Boniface’s crew is at work on all of the other elements of the 5,300-square-foot ranch house for the clients from Germany. The owner is Michael Behrens, a physicist and businessman who did research and discovered the technology of compressed- earth blocks, or CEBs. The company that produces the Earth Press machines is Adobe International Inc., located in Milan, west of Albuquerque.

The CEBs are very dense, and heavier than adobe. “People talk about adobe as being very environmentally friendly, green, but you have to get the right mix, mix it up, then there’s the backbreaking labor of setting it in the wooden molds on the ground, then flipping the bricks, then turning them on edge, then you have to pile them on palettes and drive them to the job site.

“Also, with adobe you’re limited in how many courses you can do in a day, because the weight can squish out mortar and you need to let it dry.”

The Earth Press machine delivers the blocks — each one 8 x 12 x 4 inches — near the wall being built, and you can move the machine to follow the wallmaking process. The exterior walls for the ranch house are 20 inches thick and the interior walls are 12 inches.

In the typical CEB building, once the the walls are complete, a steel-reinforced concrete bond beam is poured around the wall tops to add strength and anchor the roof structure. Channels for wiring and plumbing are cut into the walls, then nylon or wire mesh is nailed onto the walls prior to stuccoing outside and plastering inside.

Like adobe bricks, compressed-earth blocks provide great thermal mass but little insulation value. “CID requires that we add insulation and we’ll do sprayed-foam insula- tion on the exterior,” Boniface said. “One thing that makes me sleep better is that when you spray foam, it also helps to tie the wall together, plus it tightens up the house. This will be pretty air-tight.”

CEBs offers building-design possibilities similar to what you have working with adobe. And of course both strate- gies use earth as the raw material. “The head guy in the Native American crew for the ranch house project looked around and about 20 feet away from the house site, he said, ‘ This dirt will be fine.’ I had this vision that we would have to mix different kinds of earth, but that was it.”

Henry Elkins, founder of Adobe International, said his company has worked in Africa and South America, as well as in the United States, and the local dirt has always been adequate. “It requires a good clay content and about 10 percent moisture,” he said. “When the dirt is first dug, a lot of times it’s pretty close to what we need. If it’s a little dry, we’ll sprinkle the dirt with water.”

Adobe International was established in 1980. Its resumé includes a sale of 10 Earth Press machines to the govern- ment of Panama for affordable housing. People in Zacatecas, Mexico, built 500 homes over four years, using four of the machines. And in Mali, Adobe International machines are being used to build schoolhouses.

Boniface is already planning a second CEB project: a home in Tesuque. If, in the future, he were to decide to be “Mr. CEB” in his work as a contrac- tor, he will have to decide which of the three Earth Press models to purchase. They’re priced between $25,000 and $50,000 — the top-of-the-line machine puts out 10 blocks per minute. Purchasing an Earth Press sounded like a good idea to the new owners of Creek Ranch on the Pecos River. That way, anytime they want to add an outbuilding, they can just get a three-man crew together and fire it up.

For Boniface, the best part of the Creek Ranch project came after the walls had all been raised. “The Germans had a richtfest on June 30. In Germany, the entire community shows up when the last beam is in place and they tack an evergreen on top and they have a richtfest with food and drink and the architect is supposed to talk, thanking the owner for providing work for him and all the workers, and thanking the workers for what they have done.

“It was so much fun. There were probably 150 people there sharing in this almost religious experience. We’re so used to slamming houses up and moving on, but this was all about family and community.”